Fig. 2.

A: Representative immunoblots demonstrating the effects of the superoxide dismutase (SOD) mimic manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP; 50 μM, 60 min; SOD lanes) compared with untreated controls (C) on the expression of vascular-endothelial (VE-)cadherin, endothelial nitric oxide synthase (eNOS), Tyr⁴¹⁶ phosphorylated Src, and total Src in aging rat tail arteries. Arteries were processed using sequential lysis in Triton X-100 (TTX)-containing buffer (TTX-soluble fraction) followed by SDS-containing buffer (TTX-insoluble or SDS fraction) (4). Immunoblots were obtained using the same lysate. MnTMPyP increased the level of VE-cadherin in the TTX-insoluble component, which was associated with decreased phosphorylation of Src relative to total Src. MnTMPyP did not significantly affect eNOS expression (from 100.0 + 9.8% in controls to 85.2 + 11.3% in MnTMPyP-treated arteries, respectively, n = 10, P = not significant). B: representative immunoblots demonstrating the expression of VE-cadherin, eNOS, Tyr⁴¹⁶ phosphorylated Src, and total Src in aging (Age) compared with young (Yng) rat tail arteries. As previously described (4), the level of VE-cadherin in the TTX-insoluble component was reduced in aging compared with young arteries, which was associated with increased phosphorylation of Src relative to total Src. Expression of eNOS was significantly increased in aging compared with young rat tail arteries (150.9 + 17.2% and 100.0 + 8.7%, respectively, n = 13, P < 0.01).